Add workaround for Carbon 3 in occursAt

This should fix #164 until a proper fix in Carbon itself

Author: rlanvin

CHANGELOG.md

@@ -7,6 +7,10 @@
 - Drop support for PHP < 7.3 [#119](https://github.com/rlanvin/php-rrule/issues/119)
 - Add support for PHP 8.4
 
+### Fixed
+
+- Added a workaround for a Carbon 3 bug that makes occursAt fail in some cases [#164](https://github.com/rlanvin/php-rrule/issues/164)
+
 ## [2.6.0] - 2025-04-25
 
 ### Added

composer.json

@@ -23,6 +23,7 @@
     },
     "require-dev": {
         "phpunit/phpunit": "^9.0",
-        "phpmd/phpmd" : "@stable"
+        "phpmd/phpmd" : "@stable",
+        "nesbot/carbon": "*"
     }
 }

src/RRule.php

@@ -71,6 +71,30 @@ function is_leap_year($year)
 	return true;
 }
 
+/**
+ * Carbon 3 specific workaround - shouldn't be necessary but here we are.
+ * Original bug: https://github.com/briannesbitt/Carbon/issues/3018
+ * Workaround could be removed if the bug is fixed
+ * 
+ * @see https://github.com/rlanvin/php-rrule/issues/164
+ * @return int
+ */
+function date_interval_days(\DateInterval $interval): int
+{
+	if ($interval->days !== false) {
+		return $interval->days;
+	}
+
+	// if days is false, we might be dealing with Carbon.
+	// we try to get it from format() instead, and cast it to int
+	$days = $interval->format('%a');
+	if ($days !== '(unknown)' && is_numeric($days)) {
+		return (int) $days;
+	}
+
+	throw new \RuntimeException("Unable to get days from DateInterval. This shouldn't happen. If you are using a custom date library, trying passing a normal \DateTime.");
+}
+
 /**
  * Implementation of RRULE as defined by RFC 5545 (iCalendar).
  * Heavily based on python-dateutil/rrule
@@ -847,37 +871,37 @@ public function occursAt($date)
 				// count nb of days and divide by 7 to get number of weeks
 				// we add some days to align dtstart with wkst
 				$diff = $date->diff($this->dtstart);
-				$diff = (int) (($diff->days + pymod($this->dtstart->format('N') - $this->wkst,7)) / 7);
+				$diff = (int) ((date_interval_days($diff) + pymod($this->dtstart->format('N') - $this->wkst,7)) / 7);
 				if ($diff % $this->interval !== 0) {
 					return false;
 				}
 				break;
 			case self::DAILY:
 				// count nb of days
 				$diff = $date->diff($this->dtstart);
-				if ($diff->days % $this->interval !== 0) {
+				if (date_interval_days($diff) % $this->interval !== 0) {
 					return false;
 				}
 				break;
 			// XXX: I'm not sure the 3 formulas below take the DST into account...
 			case self::HOURLY:
 				$diff = $date->diff($this->dtstart);
-				$diff = $diff->h + $diff->days * 24;
+				$diff = $diff->h + date_interval_days($diff) * 24;
 				if ($diff % $this->interval !== 0) {
 					return false;
 				}
 				break;
 			case self::MINUTELY:
 				$diff = $date->diff($this->dtstart);
-				$diff  = $diff->i + $diff->h * 60 + $diff->days * 1440;
+				$diff  = $diff->i + $diff->h * 60 + date_interval_days($diff) * 1440;
 				if ($diff % $this->interval !== 0) {
 					return false;
 				}
 				break;
 			case self::SECONDLY:
 				$diff = $date->diff($this->dtstart);
 				// XXX does not account for leap second (should it?)
-				$diff  = $diff->s + $diff->i * 60 + $diff->h * 3600 + $diff->days * 86400;
+				$diff  = $diff->s + $diff->i * 60 + $diff->h * 3600 + date_interval_days($diff) * 86400;
 				if ($diff % $this->interval !== 0) {
 					return false;
 				}

tests/RRuleTest.php

@@ -1786,6 +1786,11 @@ public function notOccurrences()
 				array('freq' => 'secondly', 'dtstart' => '1999-09-02 09:00:00', 'INTERVAL' => 5),
 				array('1999-09-02 09:00:01')
 			),
+			// https://github.com/rlanvin/php-rrule/issues/164
+			'issue164' => [
+				"DTSTART:20250505T000000Z\nRRULE:FREQ=WEEKLY;UNTIL=20250520T000000Z;INTERVAL=2;BYDAY=MO",
+				['2025-05-12']
+			]
 		);
 	}
 
@@ -1800,6 +1805,17 @@ public function testNotOccurrences($rule, $not_occurrences)
 		}
 	}
 
+	/**
+	 * @dataProvider notOccurrences
+	 */
+	public function testNotOccurrencesWithCarbon($rule, $not_occurrences)
+	{
+		$rule = new RRule($rule);
+		foreach ($not_occurrences as $date) {
+			$this->assertFalse($rule->occursAt(new \Carbon\Carbon($date)), "Rule must not match $date");
+		}
+	}
+
 	public function rulesBeyondMaxCycles()
 	{
 		return [
@@ -2217,8 +2233,6 @@ public function testRfcStringParser($str, $occurrences)
 		}
 	}
 
-
-
 	public function testRfcStringParserWithDtStart()
 	{
 		$rrule = new RRule('RRULE:FREQ=YEARLY');